The regulation of the temperature due to heat generated inside the housing of an electronic device is an important consideration during the design of an electronic device. Cooling is important because if left unchecked, heat can cause electronic devices to malfunction during use or lead to premature device failure. As improvements in processor size and speed occur, the amount of heat generated by the larger and faster processors also increases. Additionally, improved processors require larger power supplies and auxiliary components that generate increased amounts of heat and require improved systems for heat removal.
Another factor that aggravates the need for improved heat removal cooling systems is the trend towards making computing devices such as blade server smaller and especially thinner. The trend toward smaller and thinner electronic devices having larger, faster processors renders the traditional heat removal cooling systems inadequate for several reasons.
In order to enhance the cooling capacity of a cooling device, an electrically powered blower is often mounted within or on top of a heatsink of the cooling device. In operation, the blower forces air to pass over fins of the heatsink, thus, cooling the heatsink by enhancing the heat transfer from the fins into the ambient air.
There are known devices of this type, for example, U.S. Pat. No. 6,688,379 “Heat Dissipation Device with High Efficiency”. The device described in this U.S. Pat. comprises a radial blower that produces a flow passing by heat exchanging channels of the heatsink. The radial blower comprises conventional hub electric drive spaced at a flowing part inside of a radial impeller thus restrains the air flow and therefore decrease the total amount of air passing through the heatsink. By this reason, the thermal efficiency of this heat dissipation device is insufficient.
Due to modern requirements for cooling devices, especially in respect to a combination of the thermal efficiency and an available space, flat electric drives are often used in radial blowers for cooling of electronic components. There are such devices describe in U.S. Pat. No. 6,664,673 “Cooler for Electronic Devices” and No. 6,700,781 “Heat-Dissipating Module for Removing Heat Generated from Heat-Generating Device”. Also, an invention described in U.S. Pat. No. 6,698,505 “Cooler for electronic device” discloses a crossflow blower with a radial impeller. All above mentioned inventions comprises a flat stator plate made as circuit board and a magnetized rotor fixed to a radial impeller of the blower. The flat stator and the magnetized rotor are located in two different parallel planes and separated by an air gap.
However, such arrangement cause a vibration of the flat stator and magnetized rotor due to a rise of oscillation forces in a direction perpendicular to the planes of the flat stator and the magnetized rotor. These forces determine by an interaction between magnetic poles of the stator and rotor. In one's turn the vibration generates an increasing sound level thus contradicts with modern requirements for cooling devices.
On the other hand mentioned vibration cause an energy losses thus decrease the motor efficiency of the electric drive and, correspondingly, a blower efficiency.
It would be desirable to provide integrated blower for cooling device that would overcome these problems associated with increased sound level and decreased blower efficiency.